- 888 Interfaces with 2 computer ports: rear panel Mode button must be set to 8ch (in), and 50-pin cable must be connected to "Computer 1" port.- Multiple DigiSystem INITs installed in System Folder or Extensions Folder .- Bent or broken pin on 50-pin interface cable.- TDM Ribbon cable not seated properly.- Interface cable plugged in upside down on d24, Disk I/O, or DSP Farm card.- Multiple systems installed in a single computer - If a PT Project card is in slot C, and a 442 card is in slot D, and the 442 I/O is off, the assumption is that Pro Tools will allocate the first card (lowest NuBus slot), but actually PT will try to use what it considers to be the best playback engine (in this case the 442). This happens even if the last deck used was Project, since DAE is looking for the best available deck when launching. In this scenario, you should hold down the "N" key while launching Pro Tools. This will drop you into the Playback Engine dialog so you can select the Project card.